The Adolescent Brain and Cognitive Development Study, or ABCD Study, is the largest long-term study of brain development and child health in the United States. The National Institutes of Health (NIH) funded leading researchers in the fields of adolescent development and neuroscience to conduct this project which will invite approximately 10,000 children ages 9-10 to join the study. Researchers will track their biological and behavioral development through adolescence into young adulthood.